abiotic/biotic reduction of trichloroethene and perchlorate · abiotic/biotic reduction of...
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Abiotic/Biotic Reduction of Trichloroethene and Perchlorate:
Laboratory Treatability Study for a Superfund SiteAnca G. Delgado
Assistant Professor of Environmental EngineeringArizona State University
December 12, 2019
CLUIN Webinar for Innovations in Remediation at the Center for Bio-mediated and Bio-inspired Geotechnics
Phoenix-Goodyear Airport North (PGA-N) Superfund Site, Goodyear, AZ
- Added to the NPL in 1983- Groundwater impacted by
trichloroethene (TCE) and perchlorate
- Chromium, cadmium, aluminum, and copper in certain source area soils
- Subunit A - Interbedded sands, silty sands, and clayey sands with localized sand and gravel sequences; groundwater depth 90-140 feet bgs; groundwater flow direction north-northwesterly
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Proposed source area remediation
- Five groundwater pump and treat systems returning cleaned water using reinjection, infiltration and irrigation.- In situ chemical reduction has been employed on a limited scale.- Treatability Study: develop design-related insights for a potential remedy for Subunit A source area
groundwater (approved by the EPA and contained in the Record of Decision Amendment Sep 2014). 3
Photo courtesy of Catherine Brown, EPA
Combined remedy using zero-valent iron and microbial reductive dechlorination
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Semi-batch microcosm study – TCE reductionMicrocosms – 25 g soil and 75 mL groundwater
• High ZVI: 15 g L−1 mZVI & 1.5 g L−1 nZVI
• Low ZVI: 2.5 mL spent ZVI from High ZVI
microcosms
• Fe (II)” 0.25 g L−1
• 560 mg/L lactate and 170 mg/L emulsified
vegetable oil (biostim)
• SDC-9 and ZARA-10: Dehalococcoides
mccartyi bioaugmentation cultures
Mohana Rangan et al. (in prep.)5
# = non-detect
SDC-9 and ZARA-10: Dehalococcoides mccartyi bioaugmentation cultures
Mohana Rangan et al. (in prep.)
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Semi-batch microcosm study –Perchlorate reduction
Growth of Dehalococcoides mccartyi in the presence of ZVI and Fe (II)
Mohana Rangan et al. (in prep.) 7
Microbial communities enriched in microcosms
Mohana Rangan et al. (in prep.)8
Microcosms – 25 g soil and 75 mL groundwater
• High ZVI: 15 g L−1 mZVI & 1.5 g L−1 nZVI
• Low ZVI: 2.5 mL spent ZVI from High ZVI
microcosms
• Fe (II)” 0.25 g L−1
• 560 mg/L lactate and 170 mg/L emulsified
vegetable oil (biostim)
• SDC-9 and ZARA-10: Dehalococcoides
mccartyi bioaugmentation cultures
i. Abiotic TCE reduction to ethene and ethane was highly effective at high ZVI
concentrations.
ii. Microbial perchlorate reduction was partially inhibited at high ZVI and Fe (II)
concentrations.
iii. Microbial TCE reductive dechlorination was a significant process at low but not high
ZVI concentrations
iv. Synergy between abiotic and biotic reduction processes was observed under flow-
through conditions.
v. Biostimulation/bioaugmentation (no ZVI) achieved similar outcomes in terms of
complete TCE dechlorination to ethene.
Lessons learned from treatability study
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Delgado Lab
Project team: Srivatsan Mohana Rangan, M.S.Shefali Rao, M.S.Aatikah Mouti, B.S.Gregory Lowry (collaborator)Harry BrentonLaurie LaPat-PolaskoAnca G. Delgado (co-PI)Rosa Krajmalnik-Brown (PI)
Krajmalnik-Brown LabDelgado Lab Krajmalnik-Brown Lab
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